Boom Truck LMI

[John C.]

I was finishing a project when the customer asked me to look at his boom truck. Apparently he was lifting an ecology block on a pallet onto the back of his truck with the boom and the pallet disintegrated dropping the rock into the base of the boom. Well it upset the LMI so that it won't lower the boom or extend it. It will only go up and the line will only go down.

I found a relay box in the base but there is a solenoid somewhere under the base. I can fell it kick out when the PTO is engaged but so far haven't been able to find the thing yet. I suspect there is a wire knocked loose. Is there anything specific that I can look for? I plan on tracing wires when I can get back to the site.

Thanks for any info and advice.

 

[63 caveman]

John,
First check the fuses, I've seen jolts pop them before.
What manufacture is the boom?

 

[crane operator]

Check the wiring from the anti- two block, if its loose anywhere, it would make it thing its two blocked and shut you down. Some of the overload LMI, have pressure transducers on the boom cylinder, and the shock load could have sent it dingy. The display should show if its A2b or overload that's shutting it off.

 

[John C.]

The boom is an RO Stinger and there is no display. It just won't let you boom down or extend. Typical for it thinking it has too much load at the wrong radius.

I can feel a solenoid below and in front of the control stations snapping when the PTO is engaged. From all the linkage I believe the valve is manually operated. I do have a loose wire with connectors hanging inside the base that I don't know where they go.

 

[63 caveman]

So this rig has no LMI or has it been removed or bypassed?

 

[crane operator]

Some of those small rigs just have a pressure sensor on the boom cylinder, too much pressure and it kicks out the functions, no actual radius or boom angle sensors in them like a full LMI. I don't know specifically how the Simon RO's work, sorry John, wish I could be of more help.

 

[John C.]

Thanks crane operator, that's actually what I was looking for. The unit does have anti two block and because of the boom extension being locked out as well as the boom down function I figured some type of electrical instead of an electronically controlled system. You statement makes the most sense and I need to expose the control valve block to see what is actually in there. I'll post what I find out.

 

[crane operator]

If it does have anti two block, I wouldn't be shocked if it just disconnected something in it. The overload or anti-two block both typically switch off power to the same solenoid, or bank of solenoids cutting those functions.

Its kind of back wards actually, because in a overload condition, while you may not be able to cable up ( or telescope- those are shut off), you can actually keep booming up, it won't shut you out of that. It tends to get guys in trouble when pushing chart, because it won't turn off that function, even though you should be stopping.

 

[John C.]

Got back up there again today. Found a wire from the anti-two block disconnected. The problem is I have not been able to find where it was connected in the first place. It is a two conductor that went down into the center of the mount and was just laying there. I got some ID off the ID plate. It is an RO Corp. TC2057, SN 469 0290- 051. The only thing I can figure is that there is a hook up somewhere in the tunnel underneath the valves but I have even found any wires from the relay box the go down into that area.

 

[crane operator]

Check the wiring from the anti- two block, if its loose anywhere, it would make it thing its two blocked and shut you down

YESSSS! If only I was a expert in real life, and not just on the internet.

There is no more RO stinger -terex owns the old brand- but you could just as well stand and tell your dog to get you parts and have as much luck as terex getting you something, but you really don't need factory help. They are probably just solenoids on the hydraulic coming off the valve before it goes to the cylinder and winch. There should be flat panel covers on both or one side of the control valve box, it should be pretty easy to spot once you open it up.

The a2b is usually just a loop of 12v. Power out, through the a2b switch, back to the functions, may have a separate coil/ relay in it that the a2b acts like a signal for.

The shut offs may be under the control handles on each side:

 

[John C.]

Got back to the machine today and sorted out a few of the problems and the boom at least works now.

I checked with the Terex web site and there were no dealers left in Washington State. Called the number on the web site and expected to go through the tortured path of mechanical voices and instead a very pleasent lady answered and sent me to a fella by the name of Jeff Lark in Portland, Oregon. I explained my predicament and we exchanged contact information. He said they still covered the unit and would my some calls and send the parts list and wiring schematics as soon as he could. The next morning the info was in the email.

Spent a bit of time over the weekend figuring out how the system was supposed to work. I had figured out that someone had hacked into the wiring and bypassed the anti 2 block. They went to the pressure switch and right back to the control box. The problem was they had apparently routed new wires through a different connector and into the box. I traced the wire back from the junction inside the box and found the place where they spliced the new wires and found a butt connector with a loose end. Stripped the wire back to a proper bare length and put a new connector in place and now the boom moves as it should. I also dismantled the switch in the anti 2 block and found the switch bad. Going to order that tomorrow and get this part of the system working proper again when I'm up there next.

Thanks to all for the suggestions and help. I found the Terex crane people real helpful so here is a shout of thanks to Jeff Lark of Terex Utilities in Portland, Oregon. Phone number (503) 924-1589.

 

[crane operator]

Glad you had good luck with terex. They keep saying they're trying to improve for the customer, I've yet to see it.

It may be because its terex utilities, rather than the crane division. They may have put the ro line there instead, and they may be more customer centered. The utility market is a little more competitive, and selling more units per year may make them more responsive.

Anyways, glad you got it sorted out.

 

[John C.]

There was a Terex dealer here in the Seattle area and they sucked rotten tomatoes. I haven't gone to them in years and apparently when I looked them up, they no longer have a phone number. The insurance adjusters that I know would not put a machine through them so I was surprised that I got good response last week just from a phone call. I'll see what happens when I try to order some parts.

Thanks again.